Electric filament lamp

ABSTRACT

The invention relates to an electric filament lamp having a tubular lamp envelope provided with a pinch seal in which two series-arranged filaments are incorporated which are coupled by a brace. The brace comprises a loop in which a supporting wire is inserted. The shape of the loop and the cross-section of the brace are non-circular, for example, elongate, so as to limit the mutual rotatability.

United States Patent 1191 De Fraeye Oct. 9, 1973 ELECTRIC FILAMENT LAMP2,218,346 10 1940 Spaeth..... 313/273 x [75] Inventor: Dirk Jules RemiDe Fraeye 3,590,305 6/1971 Decaro 313/272 Emmasingel, Eindhoven,

Netherlands Primary Examiner-David Schonberg [73] Ass1gnee: U.S. PhilipsCorporation, New A istant ExaminerPaul A. Sacher k, Att0meyFrank R.Trifari [22] Filed: Apr. 27, 1972 Appl. No.: 248,219

Foreign Application Priority Data 4 May 19, 1971 Netherlands 7106852 US.Cl 313/272, 313/273, 313/277, 313/279 Int. Cl. H0lj 1/90, HOlj 19/46,l-lOlj 19/48 Field of Search 313/272, 273, 278, 313/279, 275, 277

References Cited UNITED STATES PATENTS Eitel et a1. 33 213 7,

[57] ABSTRACT The invention relates to an electric filament lamp havinga tubular lamp envelope provided with a pinch seal in which twoseries-arranged filaments are incorporated which are coupled by a brace.The brace comprises a loop in which a supporting wire is inserted. Theshape of the loop and the cross-section of the brace are non-circular,for example, elongate, so as to limit the mutual rotatability.

4 Claims, 2 Drawing Figures 'PATENTEU [ET 731 ELECTRIC FILAMENT LAMP Theinvention relates to an electric filament lamp, in particular a halogenfilament lamp, which comprises a tubular lamp envelope having on atleast one end a pinch seal with current conductors incorporated therein,two series-arranged filaments being stretched in the longitudinaldirection of the lamp envelope, said filaments being connectedelectrically at one of their ends to the current conductors and, attheir ends most remote from the pinch seal, being coupled by means of abrace which in or near the centre of its length comprises at least oneloop in which the end of a supporting wire fixed in the lamp envelope issecured, the loop being secured to the supporting wire so as to be nonrotatable in the plane in-which the loop is located. Such a filamentlamp is known, inter alia, from the Dutch published Pat. application No.6,902,879.

The lamp described in the said Dutch patent application comprises asupporting wire of which the end inserted in the loop extends coaxiallywith the lamp envelope, the supporting wire being formed from a circularwire. As a result of this it is achieved that the filaments permanentlyassume a prescribed position in the lamp envelope. In the knownconstruction, the loop of the brace is secured to the end of thesupporting wire by means of a spot weld. As a result of this the braceis prevented from pivoting about the supporting wire. Any pivoting ofthe brace relative to the supporting wire would actually have for itsresult that the filaments do not assume the prescribed position in thelamp envelope.

It is the object of the invention to provide a lamp construction inwhich the spot welding of the loop to the supporting wire becomessuperfluous.

For that purpose, the electric filament lamp according to the inventionis characterized in that the loop and the cross-section of thesupporting wire have noncircular shapes which have been chosen to be sothat in the assembled condition of the loop and the supporting wire theylimit the mutual rotatability thereof.

As a result of the cooperation of the non-circular shape of the end ofthe supporting wire and the likewise non-circular shape of the loop inthe brace, pivoting of the brace relative to the supporting wire isprevented. As a result of this the filament will permanently assume theprescribed position in the lamp envelope.

A favourable embodiment of the electric filament lamp according to theinvention is characterized in that at least at the area of theconnection to the loop, the supporting wire comprises at least one flatside against "which a part of the loop bears. Preferably, the supportingwire has an elongate cross-section at least at the area of theconnection to the loop.

The invention will be described in greater detail with reference to thedrawing.

In the drawing,

FIG. 1 shows an embodiment of the lamp according to the invention andFIG. 2 shows the brace used therein with the end of the supporting wireincorporated in the loop.

The filament lamp shown in FIG. 1 comprises a lamp envelope 1 which isclosed at its baseby a pinch 2. Incorporated in the pinch are foils 3, 4to which the contact members 5, 6 projecting from the lamp and themandrils 7, 8 are secured. The helically wound filaments 9, 10 arestretched in the lamp envelope 1 and are slid with their one end overthe mandrils 7 and 8, respectively, and are secured to the wire brace 11with their other end. The filaments 9 and 10 are connected in series bythe brace 11. Furthermore incorporated in the lamp envelope 1 is asupyorting wire 12 which at its one end is sealed in the pinch 2 and atits other end supports in the space 13 which remains after sealing theexhaust tube. On the side of the pinch, the filaments 9, 10 and thesupporting wire 12 are supported by a quartz beam 14. y

In this embodiment the supporting wire is formed from a molybdenum wirehaving a square cross-section (FIG. 2). The brace 11 is wound around theend 15 of the supporting wire 12, as a result of which a loop 16 isformed which is present in the centre of the brace. As a result of thesquare shape of the loop 16, pivoting of the brace around the lamp axisis prevented. The fil aments 9, 10 will thus assume the desirableposition in the lamp envelope also when the lamp has been in operationfor some time.

Of course, a circular supporting wire may also be used, which has anon-circular, for example flattened, cross-section only at the area ofthe loop.

Furthermore it is possible to wind the brace more than once around thesupporting wire, so that a number of loops are formed.

What is claimed is:

1. An electric filament lamp comprising a tubular lamp envelope havingon at least one end a pinch seal with current conductors incorporatedtherein, two series-arranged filaments being stretched in thelongitudinal direction of the lamp envelope, said filaments beingconnected electrically atone of their ends to the current conductorsand, at their ends most remote from the pinch seal, being coupled bymeans of a brace which near the centre of its length comprises at leastone loop in which the end of a supporting wire fixed in the lampenvelope is secured, the loop being secured to the supporting wire so asto be non-rotatable in the plane in which the loop is located, andwherein the loop and the cross-section of the supporting wire havenoncircular shapes which have been chosen to be so that in the assembledcondition of the loop and the supporting wire they limit the mutualrotatability thereof.

2. An electric filament lamp as claimed in claim 1, wherein at least atthe area of the connection to the loop, the supporting wire has at leastone flat side against which a part of the loop bears.

3. An electric filament lamp as claimed in claim 1, wherein at least atthe area of the connection to the loop, the supporting wire has anelongate cross-section.

4. An electric filament lamp as claimed in claim 1 wherein thesupporting wire has a rectangular cross section, at least at the area ofconnection to the loop.

1. An electric filament lamp comprising a tubular lamp envelope havingon at least one end a pinch seal with current conductors incorporatedtherein, two series-arranged filaments being stretched in thelongitudinal direction of the lamp envelope, said filaments beingconnected electrically at one of their ends to the current conductorsand, at their ends most remote from the pinch seal, being coupled bymeans of a brace which near the centre of its length comprises at leastone loop in which the end of a supporting wire fixed in the lampenvelope is secured, the loop being secured to the supporting wire so asto be nonrotatable in the plane in which the loop is located, andwherein the loop and the cross-section of the supporting wire havenoncircular shapes which have been chosen to be so that in the assembledcondition of the loop and the supporting wire they limit the mutualrotatability thereof.
 2. An electric filament lamp as claimed in claim1, wherein at least at the area of the connection to the loop, thesupporting wire has at least one flat side against which a part of theloop bears.
 3. An electric filament lamp as claimed in claim 1, whereinat least at the area of the connection to the loop, the supporting wirehas an elongate cross-section.
 4. An electric filament lamp as claimedin claim 1 wherein the supporting wire has a rectangular cross section,at least at the area of connection to the loop.